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Reproduction and Domestication of Flowering Plants. Pollination - wind, insects birds. transfer of pollen from an anther to the stigma of a carpel Pollen tube is formed when pollen lands on stigma
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Pollination - wind, insects birds • transfer of pollen from an anther to the stigma of a carpel • Pollen tube is formed when pollen lands on stigma • Double fertilization – 1 sperm nucleus unites with the egg nucleus 2n zygote mitosis to form embryo • Other sperm nucleus unties with polar nuclei of central cell and forms 3n endosperm cell • Endosperm nourishes embryo and seedling during development
Mutualism and Coevolution • Many species of flowering plants have evolved with specific animal pollinators – mutualism • The joint evolution of two interacting species, each in response to selection imposed by the other – coevolution!
Flower parts • sepal – green, protects bud • Petal – specific to pollinator, wind pollination may not have flowers • Stamen – male • anther -pollen grains produced here from microspores • filament • Carpel – female • Stigma – sticky knob • Style - stalk • Ovary – base, contains ovules
Ovary = Fruit • Contains ovules, which develops into seeds. • Fruit protects the seeds and • aids in their dispersal by • wind and animals.
Seeds • As seed matures, it enters dormancy • Low metabolic rate, growth and development suspended • Resumes growth under good conditions, • fire, rain temperature can break dormancy
Seed Germination • Imbibing water causes seed to expand and rupture seed coat and triggers growth • Timing and coordination of breaking seed dormancy and initiation of germination is important. • Environmental cues and cell signaling
Flowering plants reproduce sexually or asexually or both • Asexual reproduction is called vegetative reproduction – clones • Self fertilization • Grafting, cuttings, test tube cloning • For genetic variation, plants can have self – incompatibility – rejects own pollen
Genetic Engineering with plants • Artificial selection • Conversion of plant material to sugars to make alcohols and distilled to yield biofuels. • GMO’s – golden rice